Preprints
https://doi.org/10.5194/tc-2021-137
https://doi.org/10.5194/tc-2021-137

  29 Jun 2021

29 Jun 2021

Review status: this preprint is currently under review for the journal TC.

Assessing volumetric change distributions and scaling relations of retrogressive thaw slumps across the Arctic

Philipp Bernhard1, Simon Zwieback2, Nora Bergner1, and Irena Hajnsek1,3 Philipp Bernhard et al.
  • 1Institute of Environmental Engineering, ETH Zurich, 8093 Zurich, Switzerland ETH Zürich
  • 2Geophysical Institute, University of Alaska Fairbanks, Fairbanks, AK 99775 USA
  • 3Microwaves and Radar Institute, German Aerospace Center (DLR) e.V., 82234 Wessling, Germany

Abstract. Arctic ice-rich permafrost is becoming increasingly vulnerable to terrain altering thermokarst, and among the most rapid and dramatic of these changes are retrogressive thaw slumps (RTS). They initiate when ice-rich soils are exposed and thaw, leading to the formation of a steep headwall which retreats during the summer months. These impacts, the distribution and scaling laws governing RTS changes within and between regions are unknown. Using TanDEM-X-derived digital elevation models, we estimated RTS volume and area changes over a 5-year period. We contrasted 9 regions (Eurasia: 4, North America: 5), with a total size of 220,000 km3, and over that time all 1853 RTSs combined mobilized a total volume of 17 · 106 m3 yr−1 corresponding to a volumetric change density of 77 m3 yr−1 km−2. Our remote sensing data revealed inter-regional differences in mobilized volumes, scaling laws and terrain controls. The area-to-volume scaling could be well described by a power law with an exponent of 1.15 across all regions, however the individual regions had scaling exponents ranging from 1.05 to 1.37 indicating that regional characteristics need to be taken into account when estimating RTS volumetric change from area change. The distributions of RTS area and volumetric change rates followed an inverse gamma function with a distinct peak and an exponential decrease for the largest RTSs. We found that distributions in the high Arctic were shifted towards larger values. Among the terrain controls on RTS distributions that we examined, slope, adjacency to waterbodies and aspect, the latter showed the greatest, but regionally variable association with thaw slump occurrence. Accounting for the observed regional differences in volumetric change distributions, scaling relations and terrain controls may enhance the modelling and monitoring of Arctic carbon, nutrient and sediment cycles.

Philipp Bernhard et al.

Status: open (until 28 Aug 2021)

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Philipp Bernhard et al.

Data sets

Dataset for Assessing volumetric change distributions and scaling relations of thaw slumps across the Arctic Philipp Bernhard https://doi.org/10.3929/ethz-b-000482449

Philipp Bernhard et al.

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Short summary
We present an investigation of an arctic thaw slumps in 10 study regions across the arctic. These slumps have major impacts on the arctic hydrology and ecosystems, and can also reinforce climate change by the mobilization carbon. Using time-series of digital elevation models we found that thaw slump change rates follow a specific type of distribution that is known from landslides in more temperate landscapes and that the 2D-area change is strongly related to the 3D-volumetric change.